Why thread join is needed after blocking call of future.get

Question

Hi

If I am not wrong , we need to join thread object so that main thread wait for thread to get completed. Without doing so, exit will be bad exit.

Also, future.get() is a blocking call and will wait until thread function is completed.

With these two statement , I thought we don't need to join thread if we have used future.get(). Is this correct?

If not , why?
If yes, why below code has issue if I comment t.join() line in main function?

https://sololearn.com/compiler-playground/cFn1Tvsfe4dm/?ref=app

Answer 1

get does not handle cleanup.

Answer 2

the thread object have to be destructed. it have to be joined for it to happen.

Answer 3

https://stackoverflow.com/questions/34411772/why-do-i-need-to-join-a-thread-even-if-i-use-stdfutureget

Answer 4

Sounds good. What actually cleanup does? Just curious to know. Is it relayed to pcb (process control board) data management taken care by OS?